I don't understand this argument. If you do something abusive in front of me ... I will do what a robot will do. I will stop. Because I don't want to crash. I might open the window and yell some profanities at you ... but I can do that anyway, regardless of who triggered the stop, whether it was me or the on-board computer.
If you're arguing that the on-board computer has better reflexes and therefore people will engage in even more demented behavior ... that penetration level would have to be 99%. If it's something like 90%, then 1 out of 10 times you do something that abusive will result in a crash and you'll die.
By the time penetration reaches 99%, you essentially have all cars with automation built in and it's likely that using that automation will be mandatory. Cars that aren't automated will be illegal on public roads exactly because of this problem.